The restoration of teeth commonly involves the use of (meth)acrylate-based free-radically polymerizable resins that can be chemically cured or light cured. Chemical curing typically involves a redox system with a peroxide oxidizing agent and an amine reducing agent that produces free radicals that initiate polymerization. Light curing typically involves a photoinitiator system that produces free radicals upon exposure to light.
Certain photoinitiator systems that have been introduced for use in dental restorative compositions include systems that produce free radicals via visible light (400-1000 nm). Photoinitiator systems also have been used in conjunction with cationically curing dental compositions, for example epoxy-based resins, by way of a cationic ring-opening polymerization curing mechanism. For example, ternary photoinitiator systems comprising an iodonium salt, a visible light absorber, and an electron donor have been utilized for curing both free-radically cured (meth)acrylate resins and cationically cured epoxy resins. Additionally, polycyclic aromatics have also been described for use as electron donors in cationically curing epoxy resin systems. Although these systems represent an improvement on older systems, they can sometimes experience sluggish or incomplete cure under certain conditions. Consequently, a need remains for polymerizable dental compositions (e.g., dental adhesives) with better curing performance than conventional systems, while still exhibiting satisfactory bond strengths.